Neural-net-based cell deconvolution from DNA methylation reveals tumor microenvironment associated with cancer prognosis

DNA methylation is a pivotal epigenetic modification that defines cellular identity. While cell deconvolution utilizing this information is considered useful for clinical practice, current methods for deconvolution are limited in their accuracy and resolution. In this study, we collected DNA methylation data from 945 human samples derived from various tissues and tumor-infiltrating immune cells and trained a neural network model with them. The model, termed MEnet, predicted abundance of cell population together with the detailed immune cell status from bulk DNA methylation data, and showed consistency to those of flow cytometry and histochemistry. MEnet was superior to the existing methods in the accuracy, speed, and detectable cell diversity, and could be applicable for peripheral blood, tumors, cell-free DNA, and formalin-fixed paraffin-embedded sections. Furthermore, by applying MEnet to 72 intrahepatic cholangiocarcinoma samples, we identified immune cell profiles associated with cancer prognosis. We believe that cell deconvolution by MEnet has the potential for use in clinical settings.

Downregulation of TCF7 and LEF1 is a key determinant of tumor-infiltrating regulatory T-cell function

Forkhead box P3 (Foxp3)-expressing regulatory T (Treg) cells play essential roles in immune homeostasis but also contribute to establish a favorable environment for tumor growth by suppressing anti-tumor immune responses. It is thus necessary to specifically target tumor-infiltrating Treg cells to minimize effects on immune homeostasis in cancer immunotherapy. However, molecular features that distinguish tumor-infiltrating Treg cells from those in secondary lymphoid organs remain unknown. Here we characterize distinct features of tumor-infiltrating Treg cells by global analyses of the transcriptome and chromatin landscape. They exhibited activated phenotypes with enhanced Foxp3-dependent transcriptional regulation, yet being distinct from activated Treg cells in secondary lymphoid organs. Such differences may be attributed to the extensive clonal expansion of tumor-infiltrating Treg cells. Moreover, we found that TCF7 and LEF1 were specifically downregulated in tumor-infiltrating Treg cells both in mice and humans. These factors and Foxp3 co-occupied Treg suppressive function-related gene loci in secondary lymphoid organ Treg cells, whereas the absence of TCF7 and LEF1 accompanied altered gene expression and chromatin status at these gene loci in tumor-infiltrating Treg cells. Functionally, overexpression of TCF7 and LEF1 in Treg cells inhibited the enhancement of Treg suppressive function upon activation. Our results thus show the downregulation of TCF7 and LEF1 as markers of highly suppressive Treg cells in tumors and suggest that their absence controls the augmentation of Treg suppressive function in tumors. These molecules may be potential targets for novel cancer immunotherapy with minimum effects on immune homeostasis.

Single-cell transcriptome landscape of circulating CD4+ T cell populations in autoimmune diseases

CD4+ T cells are key mediators of various autoimmune diseases; however, their role in disease progression remains unclear due to cellular heterogeneity. Here, we evaluated CD4+ T cell subpopulations using decomposition-based transcriptome characterization and canonical clustering strategies. This approach identified 12 independent gene programs governing whole CD4+ T cell heterogeneity, which can explain the ambiguity of canonical clustering. In addition, we performed a meta-analysis using public single-cell datasets of over 1.8 million peripheral CD4+ T cells from 953 individuals by projecting cells onto the reference and cataloging cell frequency and qualitative alterations of the populations in 20 diseases. The analyses revealed that the 12 transcriptional programs were useful in characterizing each autoimmune disease and predicting its clinical status. Moreover, genetic variants associated with autoimmune diseases showed disease-specific enrichment within the 12 gene programs. The results collectively provide a landscape of single-cell transcriptomes of CD4+ T cell subpopulations involved in autoimmune disease.

S-531011, a Novel Anti-Human CCR8 Antibody, Induces Potent Antitumor Responses through Depletion of Tumor-Infiltrating CCR8-Expressing Regulatory T Cells

Although regulatory T cells (Treg) are inhibitory immune cells that are essential for maintaining immune homeostasis, Tregs that infiltrate tumor tissue promote tumor growth by suppressing antitumor immunity. Selective reduction of tumor-infiltrating Tregs is, therefore, expected to activate antitumor immunity without affecting immune homeostasis. We previously reported that selective Treg depletion targeted by a C-C motif chemokine receptor 8 (CCR8) resulted in induction of strong antitumor immunity without any obvious autoimmunity in mouse models. Thus, herein, we developed a novel humanized anti-CCR8 monoclonal antibody, S-531011, aimed as a cancer immunotherapy strategy for patients with cancer. S-531011 exclusively recognized human CCR8 among all chemokine receptors and showed potent antibody-dependent cell-mediated cytotoxicity activity toward CCR8+ cells and neutralization activity against CCR8-mediated signaling. We observed that S-531011 reduced tumor-infiltrating CCR8+ Tregs and induced potent antitumor activity in a tumor-bearing human-CCR8 knock-in mouse model. Moreover, combination therapy with S-531011 and anti-mouse programmed cell death 1 (PD-1) antibody strongly suppressed tumor growth compared with anti-PD-1 antibody alone with no observable adverse effects. S-531011 also depleted human tumor-infiltrating Tregs, but not Tregs derived from human peripheral blood mononuclear cells. These results suggest that S-531011 is a promising drug for inducing antitumor immunity without severe side effects in the clinical setting.

Increased anti-oxidative action compensates for collagen tissue degeneration in vitiligo dermis

Vitiligo is a common depigmentation disorder characterized by the selective loss of melanocytes. In our daily clinic experience, we noticed that the skin tightness of hypopigmented lesions would be more evident in comparison to that of uninvolved perilesional skin in vitiligo patients. Therefore, we hypothesized that collagen homeostasis might be maintained in vitiligo lesions, irrespective of the substantial excessive oxidative stress that occurs in association with the disease. We found that the expression levels of collagen-related genes and anti-oxidative enzymes were upregulated in vitiligo-derived fibroblasts. Abundant collagenous fibers were observed in the papillary dermis of vitiligo lesions in comparison to uninvolved perilesional skin by electron microscopy. The production of matrix metalloproteinases that degraded collagen fibers was suppressed. The deposition of acrolein adduct protein, which is a product of oxidative stress, was significantly reduced in vitiligo dermis and fibroblasts. As part of the mechanism, we found upregulation of the NRF2 signaling pathway activity, which is an important defense system against oxidative stress. Taken together, we demonstrated that the anti-oxidative action and collagen production were upregulated and that the collagen degeneration was attenuated in vitiligo dermis. These new findings may provide important clues for the maintenance of antioxidant ability in vitiligo lesions.

Identification of the novel FOXP3-dependent Treg cell transcription factor MEOX1 by high-dimensional analysis of human CD4+ T cells

CD4+ T cells play a central role in the adaptive immune response through their capacity to activate, support and control other immune cells. Although these cells have become the focus of intense research, a comprehensive understanding of the underlying regulatory networks that orchestrate CD4+ T cell function and activation is still incomplete. Here, we analyzed a large transcriptomic dataset consisting of 48 different human CD4+ T cell conditions. By performing reverse network engineering, we identified six common denominators of CD4+ T cell functionality (CREB1, E2F3, AHR, STAT1, NFAT5 and NFATC3). Moreover, we also analyzed condition-specific genes which led us to the identification of the transcription factor MEOX1 in Treg cells. Expression of MEOX1 was comparable to FOXP3 in Treg cells and can be upregulated by IL-2. Epigenetic analyses revealed a permissive epigenetic landscape for MEOX1 solely in Treg cells. Knockdown of MEOX1 in Treg cells revealed a profound impact on downstream gene expression programs and Treg cell suppressive capacity. These findings in the context of CD4+ T cells contribute to a better understanding of the transcriptional networks and biological mechanisms controlling CD4+ T cell functionality, which opens new avenues for future therapeutic strategies.

Mature dendritic cells enriched in regulatory molecules may control regulatory T cells and the prognosis of head and neck cancer

We previously reported that regulatory T (Treg) cells expressing CTLA-4 on the cell surface are abundant in head and neck squamous cell carcinoma (HNSCC). The role of expanded Treg cells in the tumor microenvironment of HNSCC remains unclear. In this study, we reveal that the tumor microenvironment of HNSCC is characterized by the high expression of genes related to Treg cells, dendritic cells (DCs), and interleukin (IL)-17-related molecules. Increased expression of IL17A, IL17F, or IL23A contributes to a favorable prognosis of HNSCC. In the tumor microenvironment of HNSCC, IL23A and IL12B are expressed in mature dendritic cells enriched in regulatory molecules (mregDCs). The mregDCs in HNSCC are a migratory and mature phenotype; their signature genes strongly correlate with Treg signature genes in HNSCC. We also observed that IL17A was highly expressed in Th17 cells and exhausted CD8⁺ T cells in HNSCC. These data suggest that mregDCs in HNSCC may contribute to the prognosis by balancing Treg cells and effector T cells that produce IL-17. Targeting mregDCs may be a novel strategy for developing new immune therapies against HNSCC.

Myasthenia gravis-specific aberrant neuromuscular gene expression by medullary thymic epithelial cells in thymoma

Myasthenia gravis (MG) is a neurological disease caused by autoantibodies against neuromuscular-associated proteins. While MG frequently develops in thymoma patients, the etiologic factors for MG are not well understood. Here, by constructing a comprehensive atlas of thymoma using bulk and single-cell RNA-sequencing, we identify ectopic expression of neuromuscular molecules in MG-type thymoma. These molecules are found within a distinct subpopulation of medullary thymic epithelial cells (mTECs), which we name neuromuscular mTECs (nmTECs). MG-thymoma also exhibits microenvironments dedicated to autoantibody production, including ectopic germinal center formation, T follicular helper cell accumulation, and type 2 conventional dendritic cell migration. Cell–cell interaction analysis also predicts the interaction between nmTECs and T/B cells via CXCL12-CXCR4. The enrichment of nmTECs presenting neuromuscular molecules within MG-thymoma is further confirmed immunohistochemically and by cellular composition estimation from the MG-thymoma transcriptome. Altogether, this study suggests that nmTECs have a significant function in MG pathogenesis via ectopic expression of neuromuscular molecules.

The impact of CCR8+ regulatory T cells on cytotoxic T cell function in human lung cancer

Regulatory T cells (Tregs) suppress the host immune response and maintain immune homeostasis. Tregs also promote cancer progression and are involved in resistance to immune checkpoint inhibitor treatments. Recent studies identified selective CCR8 expression on tumor-infiltrating Tregs; CCR8+ Tregs have been indicated as a possible new target of cancer immunotherapy. Here, we investigated the features of CCR8+ Tregs in lung cancer patients. CCR8+ Tregs were highly activated and infiltration of CCR8+ Tregs in tumors was associated with poor prognosis in lung cancer patients. We also investigated their immune suppressive function, especially the influence on cytotoxic T lymphocyte cell function. The Cancer Genome Atlas analysis revealed that CD8 T cell activities were suppressed in high CCR8-expressing tumors. Additionally, depletion of CCR8+ cells enhanced CD8 T cell function in an ex vivo culture of lung tumor-infiltrating cells. Moreover, CCR8+ Tregs, but not CCR8− Tregs, induced from human PBMCs markedly suppressed CD8 T cell cytotoxicity. Finally, we demonstrated the therapeutic effect of targeting CCR8 in a murine model of lung cancer. These findings reveal the significance of CCR8+ Tregs for immunosuppression in lung cancer, especially via cytotoxic T lymphocyte cell suppression, and suggest the potential value of CCR8-targeted therapy for cancer treatment.

Angelica keiskei (Ashitaba) has potential as an antithrombotic health food

Angelica keiskei (Ashitaba) is a large perennial herb that is native to the Pacific coast of Japan. It has recently become popular as a healthy food in Asian countries because it might have various physiological benefits including antithrombotic properties. Most studies of the bioactive constituents from Ashitaba have focused on the activities of the major chalcones, xanthoangelol and 4-hydroxyderricin. However, other chalcones, flavanones and coumarins have also been isolated from Ashitaba, precisely characterized, and investigated in vivo. Platelets play a key role in haemostasis and wound healing processes. Dysregulated platelet activity is associated with the progression of platelet aggregation and decreased venous blood flow, which results in thrombotic diseases. A minor chalcone, xanthoangelol E, inhibits TXB2 synthesis in rabbit platelets, which seems to be the source of the belief that Ashitaba has antithrombotic properties. However, recent data showed that xanthoangelol and 4-hydroxyderricin inhibited the aggregation of rabbit platelets. Platelet aggregation stimulated by collagen was also inhibited in whole blood incubated with Xanthoangelol or 4-hydroxyderricin. Plasminogen activator inhibitor-1 is the primary physiological inhibitor of tissue type plasminogen activator, a key protease of the fibrinolytic system. An increase in plasma of this inhibitor is associated with thrombotic conditions. Ashitaba yellow exudate inhibited the elevation of plasma plasminogen activator inhibitor-1 in mice induced by obesity or chronic low-grade inflammation. These studies showed the yellow exudate from stem cuttings and chalcones isolated from Ashitaba roots and leaves might have antithrombotic activity. This article reviews the possible antithrombotic properties of Ashitaba.

873 S-531011, a novel anti-human CCR8 antibody: anti-tumor responses through depletion of tumor-infiltrating CCR8-positive Tregs

Background

Regulatory T cells (Tregs) are suppressive immune cells required for the maintenance of immune homeostasis, but tumor-infiltrating Tregs are known to suppress the antitumor immune system and promote tumor progression. Therefore, selective reduction of tumor-infiltrating Tregs is anticipated to reinvigorate antitumor immunity without inducing autoimmunity. S-531011 is a novel anti-human IgG1 antibody targeting human CCR8 (C-C motif chemokine receptor 8) which is selectively expressed in tumor-infiltrating Tregs, with both in vitro antibody dependent cellular cytotoxicity (ADCC) against CCR8-expressing cells and neutralizing activity against CCL1-CCR8 signaling. Here, to evaluate antitumor activities and safety aspects of S-531011, we conducted non-clinical pharmacology studies of S-531011 using human CCR8 knock-in (KI) mice and human tissues.

Methods

S-531011 was administrated to CT26WT tumor-bearing hCCR8-KI mice, and the effect on the presence of tumor-infiltrating CCR8+ Treg and tumor growth were evaluated. We also investigated the antitumor efficacy of S-531011 in combination with anti-mouse PD-1 antibody. Next, human lung cancer tissues and human NK-cells were co-cultured, and the ex vivo ADCC against tumor-infiltrating Tregs by S-531011 was verified. We also incubated human peripheral blood-derived mononuclear cells (PBMC) from healthy individuals with S-531011 to investigate the effects on the proportion of Tregs in human PBMC.

Results

Intravenous administration of S-531011 to CT26WT tumor-bearing hCCR8-KI mice significantly reduced tumor-infiltrating CCR8+ Tregs and markedly suppressed tumor growth. Furthermore, the combined therapy of S-531011 with anti-mouse PD-1 antibody showed greater anti-tumor effect than monotherapy without any apparent side effects. Ex vivo ADCC studies using human lung cancer tissues and FCM analysis of CCR8 expression in tumor-infiltrating Tregs suggested that most of the tumor-infiltrating CCR8+ Tregs were depleted by S-531011. On the other hand, S-531011 didn’t reduce Tregs in human PBMC.

Conclusions

S-531011 is a promising drug which has a strong antitumor effect by depleting tumor-infiltrating CCR8+ Tregs, as a not only monotherapy but also combination therapy with other immune checkpoint inhibitors.

Ethics Approval

The present study was approved by the Institutional Ethics Committee of Osaka University Hospital (approved number: 13266-15) and Shionogi Co., Ltd. (approved number: 021-003). Animal studies were approved by the Institutional Animal Care and Use Committee (approved number: S20093D, S20197D and S20198D).

891 S-531011, a novel anti-human CCR8 antibody: antibody screening and evaluation of biological profiles

Background

Regulatory T cells (Tregs) are involved in tumor progression and inhibition of anti-tumor immune responses by promotion of immunological tolerance in the tumor microenvironment. On the other hand, Treg cells in peripheral blood are also essential role in preventing autoimmunity and uncontrolled inflammation. So, selective control of tumor infiltrating Treg cells might be an attractive approach of immune-oncology therapies without disrupting their systemic anti-inflammatory functions. Here, we focused on CCR8 (C-C motif chemokine receptor 8) as a target molecule which was selectively and highly expressed on tumor-infiltrating Tregs and developed a novel anti-human CCR8 specific antibody.

Methods

We immunized mice with human CCR8 by our original immunization method which could strongly induce antibodies for membrane proteins, and then constructed hybridoma cells. Anti-human CCR8 (human CCR4 as a negative control) binding assay and human CCL1-CCR8 neutralizing assay were simultaneously performed by using supernatants of hybridoma cells to isolate human CCR8 specific strong-neutralizing antibodies. After humanization and affinity maturation of some selected clones, we selected our lead antibody by binding specificity, neutralizing activity, antibody dependent cellular cytotoxicity (ADCC) and thermodynamic stability as index.

Results

We rapidly induced human CCR8 specific antibodies in mouse with our unique immunization methods and constructed thousands of hybridomas secreting anti-human CCR8 antibodies. We also successfully humanized some of lead antibodies which show high affinity and specificity and isolated novel anti-human CCR8 specific humanized antibody S-531011 as our development antibody after affinity maturation. S-531011 selectively recognizes human CCR8 on the surface of tumor-infiltrating Tregs and shows strong ADCC. While human CCL1 is known as a dominant ligand of CCR8 which binds extracellular loop2 and N-terminal of CCR8, S-531011 recognizes similar epitopes and effectively neutralizes CCL1-CCR8 signaling. Furthermore, S-531011 also shows favorable blood kinetics in vivo and potently inhibits tumor growth in tumor bearing human CCR8 knock-in mouse model.

Conclusions

We develop S-531011, a novel anti-human CCR8 humanized antibody which could selectively recognize and deplete tumor infiltrating Tregs. Based on our pre-clinical data, S-531011 has strong anti-tumor effect and we expect that it might be a potent novel tumor immuno-therapeutic agent with fewer side effect.

Ethics Approval

The present study was approved by the Institutional Ethics Committee of Osaka University Hospital (approved number: 13266-15). Animal studies were approved by the Institutional Animal Care and Use Committee (approved number: S20192D, S20197D and S20198D).

VIRTUS: a pipeline for comprehensive virus analysis from conventional RNA-seq data

Summary

The possibility that RNA transcripts from clinical samples contain plenty of virus RNAs has not been pursued actively so far. We here developed a new tool for analyzing virus-transcribed mRNAs, not virus copy numbers, in the data of bulk and single-cell RNA-sequencing of human cells. Our pipeline, named VIRTUS (VIRal Transcript Usage Sensor), was able to detect 762 viruses including herpesviruses, retroviruses and even SARS-CoV-2 (COVID-19), and quantify their transcripts in the sequence data. This tool thus enabled simultaneously detecting infected cells, the composition of multiple viruses within the cell, and the endogenous host-gene expression profile of the cell. This bioinformatics method would be instrumental in addressing the possible effects of covertly infecting viruses on certain diseases and developing new treatments to target such viruses.

Availability and implementation

: VIRTUS is implemented using Common Workflow Language and Docker under a CC-NC license. VIRTUS is freely available at https://github.com/yyoshiaki/VIRTUS.

Supplementary information

Supplementary data are available at Bioinformatics online.

Distinct Foxp3 enhancer elements coordinate development, maintenance, and function of regulatory T cells

The transcription factor Foxp3 plays crucial roles for Treg cell development and function. Conserved non-coding sequences (CNSs) at the Foxp3 locus control Foxp3 transcription, but how they developmentally contribute to Treg cell lineage specification remains obscure. Here, we show that among Foxp3 CNSs, the promoter-upstream CNS0 and the intergenic CNS3, which bind distinct transcription factors, were activated at early stages of thymocyte differentiation prior to Foxp3 promoter activation, with sequential genomic looping bridging these regions and the promoter. While deletion of either CNS0 or CNS3 partially compromised thymic Treg cell generation, deletion of both completely abrogated the generation and impaired the stability of Foxp3 expression in residual Treg cells. As a result, CNS0 and CNS3 double-deleted mice succumbed to lethal systemic autoimmunity and inflammation. Thus, hierarchical and coordinated activation of Foxp3 CNS0 and CNS3 initiates and stabilizes Foxp3 gene expression, thereby crucially controlling Treg cell development, maintenance, and consequently immunological self-tolerance.

Clinical importance of the expression of CD4+CD8+ T cells in renal cell carcinoma

OBJECTIVE

CD4+CD8+ T cells are expressed in some cancer patients including those with renal cell carcinoma (RCC). However, no reports have mentioned the clinical importance of this expression. We evaluated the expression of CD4+CD8+ T cells in patients with various cancer types to clarify clinical characteristics and prognostic importance significantly correlating with these T cells.

METHODS

Expression of CD4+CD8+ T cells was evaluated using flowcytometry in tissue-infiltrating lymphocytes extracted from 260 cancer tissues including 104 RCC samples. RNA sequencing and characterization and regression (Citrus) was used to determine characteristics. The prognostic importance of CD4+CD8+ T cells was evaluated by Cox regression analysis.

RESULTS

Among eight cancer types, expression of CD4+CD8+ T cells was significantly highest in RCC patients. According to the expression of CD4+CD8+ T cells in adjacent normal tissue-infiltrating lymphocytes, 24 patients (23.1%) were defined as being positive for CD4+CD8+ with an expression higher than 9.29% in RCC patients. Citrus showed CD8+PD-1+TIM-3+CD103- T cells to be a specific subpopulation of CD4+CD8+ T cells. RNA sequencing revealed that CD4+CD8+ T cells had significantly lower diversity than the other T cells and shared most T-cell receptor clones with CD8+ not CD4+ T cells. Expression of CD4+CD8+ T cells was identified as an independent predictor of overall survival (hazard ratio: 0.11, 95% confidence interval: 0.01-0.86, P = 0.035) in multivariate analysis.

CONCLUSIONS

The expression of CD4+CD8+ T cells was significantly up-regulated in RCC patients and correlated significantly with prognostic importance in surgically treated RCC patients.

Conversion of antigen-specific effector/memory T cells into Foxp3-expressing Treg cells by inhibition of CDK8/19

A promising way to restrain hazardous immune responses, such as autoimmune disease and allergy, is to convert disease-mediating T cells into immunosuppressive regulatory T (T_reg) cells. Here, we show that chemical inhibition of the cyclin-dependent kinase 8 (CDK8) and CDK19, or knockdown/knockout of the CDK8 or CDK19 gene, is able to induce Foxp3, a key transcription factor controlling T_reg cell function, in antigen-stimulated effector/memory as well as naïve CD4⁺ and CD8⁺ T cells. The induction was associated with STAT5 activation, independent of TGF-β action, and not affected by inflammatory cytokines. Furthermore, in vivo administration of a newly developed CDK8/19 inhibitor along with antigen immunization generated functionally stable antigen-specific Foxp3⁺ T_reg cells, which effectively suppressed skin contact hypersensitivity and autoimmune disease in animal models. The results indicate that CDK8/19 is physiologically repressing Foxp3 expression in activated conventional T cells and that its pharmacological inhibition enables conversion of antigen-specific effector/memory T cells into Foxp3⁺ T_reg cells for the treatment of various immunological diseases.

Tumour grade significantly correlates with total dysfunction of tumour tissue-infiltrating lymphocytes in renal cell carcinoma

It is important to evaluate the clinical importance of both CD8 T cells and CD4 T cells expression simultaneously because they have crucial networks in tumour targeting immune responses. In 97 RCC patients, RNA sequencing and gene set enrichment analysis of both CD8 and CD4 T cells based on the expression levels of PD-1 and TIM-3 implied that the populations of PD-1+TIM-3+ CD8 T cells and PD-1lowTIM-3 + CD4 T cells were characterized as exhausted CD8 T cells and regulatory CD4 T cells, respectively. These populations of CD4 and CD8 T cells were significantly upregulated in the patients with RCC of higher WHO/ISUP grade (grades 3, 4) (P < 0.001). Moreover, the cytokine productivities of each population in both CD4 and CD8 T cells of the higher-grade patients were significantly lower than those of the lower-grade patients (P < 0.05). Multivariate analysis showed the prognosis of patients with metastatic RCC of higher WHO/ISUP grade treated by nivolumab to be significantly worse than that of patients with lower grade (P = 0.026). This study showed that tumour grade significantly correlated with dysfunction of both CD4+ and CD8+ TILs and the efficacy of nivolumab treatment.

Regulatory T Cells and Human Disease

Naturally occurring CD4⁺ regulatory T cells (Tregs), which specifically express the transcription factor FoxP3 in the nucleus and CD25 and CTLA-4 on the cell surface, are a functionally distinct T cell subpopulation actively engaged in the maintenance of immunological self-tolerance and homeostasis. Recent studies have facilitated our understanding of the cellular and molecular basis of their generation, function, phenotypic and functional stability, and adaptability. It is under investigation in humans how functional or numerical Treg anomalies, whether genetically determined or environmentally induced, contribute to immunological diseases such as autoimmune diseases. Also being addressed is how Tregs can be targeted to control physiological and pathological immune responses, for example, by depleting them to enhance tumor immunity or by expanding them to treat immunological diseases. This review discusses our current understanding of Treg immunobiology in normal and disease states, with a perspective on the realization of Treg-targeting therapies in the clinic.

M2 Phenotype Macrophages Colocalize with Schwann Cells in Human Dental Pulp

Macrophages are immune cells with high plasticity that perform many functions related to tissue injury and repair. They are generally categorized as 2 functional phenotypes: M1 (proinflammatory) and M2 (anti-inflammatory and prohealing). To investigate the role of macrophages in human dental pulp, we examined the localization and distributional alterations of macrophages in healthy dental pulp as well as during the reparative process of pulp capping with mineral trioxide aggregate (MTA) and in cariously inflamed pulp of adult human teeth. We also quantified the populations of M1/M2 macrophages in healthy dental pulp by flow cytometric analysis. CD68⁺CD86⁺ cells (M1 phenotype) and CD68⁺CD163⁺ cells (M2 phenotype) were 2.11% ± 0.50% and 44.99% ± 2.22%, respectively, of 2.96% ± 0.41% CD68⁺ cells (pan-macrophages) in whole healthy dental pulp. Interestingly, M2 phenotype macrophages were associated with Schwann cells in healthy pulp, during mineralized bridge formation, and in pulp with carious infections in vivo. Furthermore, the M2 macrophages associated with Schwann cells expressed brain-derived neurotrophic factor (BDNF) under all in vivo conditions. Moreover, we found that plasma cells expressed BDNF. Coculture of Schwann cells isolated from human dental pulp and human monocytic cell line THP-1 showed that Schwann cells induced M2 phenotypic polarization of THP-1 cell-derived macrophages. The THP-1 macrophages that maintained contact with Schwann cells were stimulated, leading to elongation of their cell shape and expression of M2 phenotype marker CD163 in cocultures. In summary, we revealed the spatiotemporal localization of macrophages and potent induction of the M2 phenotype by Schwann cells in human dental pulp. M2 macrophages protect neural elements, whereas M1 cells promote neuronal destruction. Therefore, suppressing the neurodestructive M1 phenotype and maintaining the neuroprotective M2 phenotype of macrophages by Schwann cells may be critical for development of effective treatment strategies to maintain the viability of highly innervated dental pulp.

Dynamic Imprinting of the Treg Cell-Specific Epigenetic Signature in Developing Thymic Regulatory T Cells

Regulatory T (Treg) cells mainly develop within the thymus and arise from CD25⁺Foxp3⁻ (CD25⁺ TregP) or CD25⁻Foxp3⁺ (Foxp3⁺ TregP) Treg cell precursors resulting in Treg cells harboring distinct transcriptomic profiles and complementary T cell receptor repertoires. The stable and long-term expression of Foxp3 in Treg cells and their stable suppressive phenotype are controlled by the demethylation of Treg cell-specific epigenetic signature genes including an evolutionarily conserved CpG-rich element within the Foxp3 locus, the Treg-specific demethylated region (TSDR). Here we analyzed the dynamics of the imprinting of the Treg cell-specific epigenetic signature genes in thymic Treg cells. We could demonstrate that CD25⁺Foxp3⁺ Treg cells show a progressive demethylation of most signature genes during maturation within the thymus. Interestingly, a partial demethylation of several Treg cell-specific epigenetic signature genes was already observed in Foxp3⁺ TregP but not in CD25⁺ TregP. Furthermore, Foxp3⁺ TregP were very transient in nature and arose at a more mature developmental stage when compared to CD25⁺ TregP. When the two Treg cell precursors were cultured in presence of IL-2, a factor known to be critical for thymic Treg cell development, we observed a major impact of IL-2 on the demethylation of the TSDR with a more pronounced effect on Foxp3⁺ TregP. Together, these results suggest that the establishment of the Treg cell-specific hypomethylation pattern is a continuous process throughout thymic Treg cell development and that the two known Treg cell precursors display distinct dynamics for the imprinting of the Treg cell-specific epigenetic signature genes.

Innate Myeloid Cell Subset-Specific Gene Expression Patterns in the Human Colon are Altered in Crohn's Disease Patients

BACKGROUND/AIMS

There is a heterogeneous subset innate myeloid cells, such as macrophages and dendritic cells, in the human intestinal lamina propria. Several studies have demonstrated that these cells contribute to the maintenance of gut homeostasis through the induction of inflammatory responses and tolerance via cell type-specific mechanisms; whereas, disrupted innate immune responses are implicated in the pathogenesis of Crohn's disease (CD). However, the detailed mechanisms by which each innate myeloid subset regulates gut homeostasis and inflammation largely remain unknown. We aimed to clarify the comprehensive gene expression profiles of innate myeloid cell -subsets in the lamina propria from normal human colons (NC) and the inflamed colon sites from patients with Crohn's disease (CDi).

METHODS

We performed RNA-sequencing analysis and precise bioinformatics analysis on 3 innate myeloid cell subsets, CD14-CD11c-, CD14-CD11c+, and CD14+CD11c+CD163low cells from NC and CDi.

RESULTS

Transcriptional analysis of the 3 subsets from the NC showed distinct gene expression patterns and gene ontology (GO) enrichment analysis revealed the associated innate myeloid subset-specific biological process (BP) terms. In addition, changes in gene expression patterns were observed in innate myeloid subsets from CDi. Furthermore, the core GO-BP terms for the genes upregulated in the innate myeloid cells from CDi were distinct from those found in NC.

CONCLUSION

Our data identified the innate myeloid cell subset-specific transcriptomes and the associated enriched GO-BP terms in the NC and found these patterns were altered in CDi.

Regulatory roles of IL-10-producing human follicular T cells

Uncontrolled IgE responses drive allergies and anaphylaxis. Here, Cañete et al. describe a human follicular regulatory T cell population that does not express FOXP3 and produces abundant IL-10, which limits IgE switching. These cells appear to be key regulators of atopy.

Mucosal lymphoid tissues such as human tonsil are colonized by bacteria and exposed to ingested and inhaled antigens, requiring tight regulation of immune responses. Antibody responses are regulated by follicular helper T (T_FH) cells and FOXP3⁺ follicular regulatory T (T_FR) cells. Here we describe a subset of human tonsillar follicular T cells identified by expression of T_FH markers and CD25 that are the main source of follicular T (T_F) cell–derived IL-10. Despite lack of FOXP3 expression, CD25⁺ T_F cells resemble T reg cells in high CTLA4 expression, low IL-2 production, and their ability to repress T cell proliferation. CD25⁺ T_F cell–derived IL-10 dampens induction of B cell class-switching to IgE. In children, circulating total IgE titers were inversely correlated with the frequencies of tonsil CD25⁺ T_F cells and IL-10–producing T_F cells but not with total T reg cells, T_FR, or IL-10–producing T cells. Thus, CD25⁺ T_F cells emerge as a subset with unique T and B cell regulatory activities that may help prevent atopy.

Functional Roles of the IgM Fc Receptor in the Immune System

It is now evident from studies of mice unable to secrete IgM that both non-immune “natural” and antigen-induced “immune” IgM are important for protection against pathogens and for regulation of immune responses to self-antigens. Since identification of its Fc receptor (FcμR) by a functional cloning strategy in 2009, the roles of FcμR in these IgM effector functions have begun to be explored. Unlike Fc receptors for switched Ig isotypes (e.g., FcγRs, FcεRs, FcαR, Fcα/μR, pIgR, FcRn), FcμR is selectively expressed by lymphocytes: B, T, and NK cells in humans and only B cells in mice. FcμR may have dual signaling ability: one through a potential as yet unidentified adaptor protein non-covalently associating with the FcμR ligand-binding chain via a His in transmembrane segment and the other through its own Tyr and Ser residues in the cytoplasmic tail. FcμR binds pentameric and hexameric IgM with a high avidity of ~10 nM in solution, but more efficiently binds IgM when it is attached to a membrane component via its Fab region on the same cell surface (cis engagement). Four different laboratories have generated Fcmr-ablated mice and eight different groups of investigators have examined the resultant phenotypes. There have been some clear discrepancies reported that appear to be due to factors including differences in the exons of Fcmr that were targeted to generate the knockouts. One common feature among these different mutant mice, however, is their propensity to produce autoantibodies of both IgM and IgG isotypes. In this review, we briefly describe recent findings concerning the functions of FcμR in both mice and humans and propose a model for how FcμR plays a regulatory role in B cell tolerance.

Enzymatic Activity of HPGD in Treg Cells Suppresses Tconv Cells to Maintain Adipose Tissue Homeostasis and Prevent Metabolic Dysfunction

Regulatory T cells (Treg cells) are important for preventing autoimmunity and maintaining tissue homeostasis, but whether Treg cells can adopt tissue- or immune-context-specific suppressive mechanisms is unclear. Here, we found that the enzyme hydroxyprostaglandin dehydrogenase (HPGD), which catabolizes prostaglandin E₂ (PGE₂) into the metabolite 15-keto PGE₂, was highly expressed in Treg cells, particularly those in visceral adipose tissue (VAT). Nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ)-induced HPGD expression in VAT Treg cells, and consequential Treg-cell-mediated generation of 15-keto PGE₂ suppressed conventional T cell activation and proliferation. Conditional deletion of Hpgd in mouse Treg cells resulted in the accumulation of functionally impaired Treg cells specifically in VAT, causing local inflammation and systemic insulin resistance. Consistent with this mechanism, humans with type 2 diabetes showed decreased HPGD expression in Treg cells. These data indicate that HPGD-mediated suppression is a tissue- and context-dependent suppressive mechanism used by Treg cells to maintain adipose tissue homeostasis.

Regulatory T cells expressing abundant CTLA-4 on the cell surface with a proliferative gene profile are key features of human head and neck cancer

FOXP3⁺ regulatory T (Treg) cells suppress anti-tumor immunity. The suppression of Treg cells is regulated by cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), whose expression on the cell surface is tightly regulated. Here we found that Treg cells expressing abundant CTLA-4 on the cell surface (surface-CTLA-4⁺ Treg) were expanded in human head and neck cancer tissues. RNA sequencing of surface-CTLA-4⁺ and surface-CTLA-4^- Treg cells infiltrating human head and neck cancer tissues revealed that surface-CTLA-4⁺ Treg cells have a previously undescribed gene expression profile correlating to cell cycle, cell proliferation, and DNA replication. Moreover, surface-CTLA-4⁺ Treg cells were PD-1⁺ , actively proliferated and associated with CD45RA^- FOXP3^high Treg cells with strong suppressive function. Thus, surface-CTLA-4⁺ Treg cells with a proliferative gene expression signature and phenotype are key features of head and neck cancer. Targeting surface-CTLA-4⁺ Treg cells might be new strategies to evoke effective immune responses to head and neck cancer.

Possible antithrombotic effects of Angelica keiskei (Ashitaba)

Angelica keiskei Koidzumi (Ashitaba) is a large perennial herb that is native to the Pacific coast of Japan, and it has recently become popular as herbal medicine, dietary supplement and health food in Asian countries. The structures of various constituents isolated from Ashitaba such as chalcones, flavanones and coumarins have been precisely characterized, and many of them have bioactivities. A recent study clarified that Angelica keiskei exerts actions that lead to the prevention of thrombosis. Here, we introduce the possibility that ingesting Ashitaba could help to prevent thrombotic diseases.

Unique properties of thymic antigen-presenting cells promote epigenetic imprinting of alloantigen-specific regulatory T cells

Regulatory T cells (Tregs) are potential immunotherapeutic candidates to induce transplantation tolerance. However, stability of Tregs still remains contentious and may potentially restrict their clinical use. Recent work suggested that epigenetic imprinting of Foxp3 and other Treg-specific signature genes is crucial for stabilization of immunosuppressive properties of Foxp3⁺ Tregs, and that these events are initiated already during early stages of thymic Treg development. However, the mechanisms governing this process remain largely unknown. Here we demonstrate that thymic antigen-presenting cells (APCs), including thymic dendritic cells (t-DCs) and medullary thymic epithelial cells (mTECs), can induce a more pronounced demethylation of Foxp3 and other Treg-specific epigenetic signature genes in developing Tregs when compared to splenic DCs (sp-DCs). Transcriptomic profiling of APCs revealed differential expression of secreted factors and costimulatory molecules, however neither addition of conditioned media nor interference with costimulatory signals affected Foxp3 induction by thymic APCs in vitro. Importantly, when tested in vivo both mTEC- and t-DC-generated alloantigen-specific Tregs displayed significantly higher efficacy in prolonging skin allograft acceptance when compared to Tregs generated by sp-DCs. Our results draw attention to unique properties of thymic APCs in initiating commitment towards stable and functional Tregs, a finding that could be highly beneficial in clinical immunotherapy.

Anti-platelet effects of chalcones from Angelica keiskei Koidzumi (Ashitaba) in vivo

Angelica keiskei Koidzumi (Ashitaba) is a traditional folk medicine that is also regarded in Japan as a health food with potential antithrombotic properties. The ability of the major chalcones, xanthoangelol (XA) and 4-hydroxyderricin (4-HD) extracted from Ashitaba roots to inhibit platelet aggregation activity in vitro was recently determined. However, the anti-platelet activities of Ashitaba chalcones in vivo have remained unclear. The present study examines the anti-platelet effects of Ashitaba exudate and its constituent chalcones using mouse tail-bleeding models that reflect platelet aggregation in vivo. Ashitaba exudate and the major chalcone subtype XA, suppressed the lipopolysaccharide (LPS)-induced shortening of mouse tail bleeding. However, trace amounts of other Ashitaba chalcone subtypes including xanthoangelols B (XB), D (XD), E (XE) and F (XF) did not affect tail bleeding. These results suggest that the major chalcone subtype in Ashitaba, XA, has anti-platelet-activities in vivo.

Ultraviolet B-Induced Maturation of CD11b-Type Langerin- Dendritic Cells Controls the Expansion of Foxp3+ Regulatory T Cells in the Skin

Skin dendritic cells (DCs) are divided into several subsets with distinctive functions. This study shows a previously unappreciated role of dermal CD11b-type Langerin^- DCs in maintaining immunological self-tolerance after UVB exposure. After UVB exposure, dermal CD11b-type Langerin^- DCs upregulated surface CD86 expression, induced proliferation of Foxp3⁺ regulatory T (Treg) cells without exogenous Ags, and upregulated a set of genes associated with immunological tolerance. This Treg-expansion activity was significantly hampered by CD80/CD86 blockade in vivo. These results indicate that CD11b-type Langerin^- DCs from the UVB-exposed skin are specialized to expand Treg cells in the skin, which suppress autoimmunity.

Lamtor1 Is Critically Required for CD4+ T Cell Proliferation and Regulatory T Cell Suppressive Function

Mechanistic target of rapamycin complex (mTORC)1 integrates intracellular sufficiency of nutrients and regulates various cellular functions. Previous studies using mice with conditional knockout of mTORC1 component proteins (i.e., mTOR, Raptor, and Rheb) gave conflicting results on the roles of mTORC1 in CD4⁺ T cells. Lamtor1 is the protein that is required for amino acid sensing and activation of mTORC1; however, the roles of Lamtor1 in T cells have not been investigated. In this article, we show that Lamtor1-deficient CD4⁺ T cells exhibited marked reductions in proliferation, IL-2 production, mTORC1 activity, and expression of purine- and lipid-synthesis genes. Polarization of Th17 cells, but not Th1 and Th2 cells, diminished following the loss of Lamtor1. Accordingly, CD4-Cre-driven Lamtor1-knockout mice exhibited reduced numbers of CD4⁺ and CD8⁺ T cells at rest, and they were completely resistant to experimental autoimmune encephalomyelitis. In contrast, genetic ablation of Lamtor1 in Foxp3⁺ T cells resulted in severe autoimmunity and premature death. Lamtor1-deficient regulatory T cells survived ex vivo as long as wild-type regulatory T cells; however, they exhibited a marked loss of suppressive function and expression of signature molecules, such as CTLA-4. These results indicate that Lamtor1 plays essential roles in CD4⁺ T cells. Our data suggest that Lamtor1 should be considered a novel therapeutic target in immune systems.

IL4Rα and ADAM33 as genetic markers in asthma exacerbations and type-2 inflammatory endotype

BACKGROUND

Genetic markers of susceptibility to asthma exacerbations in adults remain unclear.

OBJECTIVE

To identify genetic markers of asthma exacerbations, particularly in patients with type-2 inflammatory endotype.

METHODS

In this observational study of patients enrolled in the Kinki Hokuriku Airway disease Conference multicenter study, frequency of exacerbations requiring systemic corticosteroids during 2 years after enrolment and associated risk factors was determined. For genetic marker analysis, interleukin-4 receptor α (IL4RA) rs8832 and a disintegrin and metalloprotease 33 (ADAM33) S_2 (rs528557), T_1 (rs2280091), T_2 (rs2280090), and V_4 (rs2787094) variants were included. Elevated serum periostin levels at enrolment (≥95 ng/mL, defined as type-2 inflammatory endotype) were considered in the analysis.

RESULTS

Among 217 patients who were successfully followed up for 2 years after enrolment, 60 patients showed at least one asthma exacerbation during the 2 years. Airflow limitation (%FEV₁ <80%) and recent exacerbations but not genetic variants were identified as risk markers of exacerbations. A total of 27 patients showed type-2 inflammatory endotype (serum periostin ≥95 ng/mL at enrolment) and subsequent exacerbations; risk factors in these patients were airflow limitation (odds ratio, 6.51; 95% confidence interval (CI): 2.37-18.6; P=.0003), GG genotype of IL4RA rs8832 (odds ratio, 4.01; 95% CI: 1.47-11.0; P=.007), and A allele of ADAM33 T_2 (odds ratio, 2.81; 95% CI: 1.05-7.67; P=.04) by multivariate analysis. In addition, GG genotype of IL4RA rs8832 was associated with type-2 endotype, whereas A allele of ADAM33 T_2 was associated with mixed type of eosinophilic/type-2 and neutrophilic inflammations.

CONCLUSIONS AND CLINICAL RELEVANCE

IL4RA and ADAM33 variants may be risk markers of asthma exacerbations in type-2 inflammatory endotype. Precise endotyping may facilitate the identification of genetic risk markers of asthma exacerbations.

Guidance of regulatory T cell development by Satb1-dependent super-enhancer establishment

Most Foxp3+ regulatory T (Treg) cells develop in the thymus as a functionally mature T cell subpopulation specialized for immune suppression. Their cell fate appears to be determined before Foxp3 expression; yet molecular events that prime Foxp3- Treg precursor cells are largely obscure. We found that Treg cell-specific super-enhancers (Treg-SEs), which were associated with Foxp3 and other Treg cell signature genes, began to be activated in Treg precursor cells. T cell-specific deficiency of the genome organizer Satb1 impaired Treg-SE activation and the subsequent expression of Treg signature genes, causing severe autoimmunity due to Treg cell deficiency. These results suggest that Satb1-dependent Treg-SE activation is crucial for Treg cell lineage specification in the thymus and that its perturbation is causative of autoimmune and other immunological diseases.

Two FOXP3(+)CD4(+) T cell subpopulations distinctly control the prognosis of colorectal cancers

CD4(+) T cells that express the forkhead box P3 (FOXP3) transcription factor function as regulatory T (Treg) cells and hinder effective immune responses against cancer cells. Abundant Treg cell infiltration into tumors is associated with poor clinical outcomes in various types of cancers. However, the role of Treg cells is controversial in colorectal cancers (CRCs), in which FOXP3(+) T cell infiltration indicated better prognosis in some studies. Here we show that CRCs, which are commonly infiltrated by suppression-competent FOXP3(hi) Treg cells, can be classified into two types by the degree of additional infiltration of FOXP3(lo) nonsuppressive T cells. The latter, which are distinguished from FOXP3(+) Treg cells by non-expression of the naive T cell marker CD45RA and instability of FOXP3, secreted inflammatory cytokines. Indeed, CRCs with abundant infiltration of FOXP3(lo) T cells showed significantly better prognosis than those with predominantly FOXP3(hi) Treg cell infiltration. Development of such inflammatory FOXP3(lo) non-Treg cells may depend on secretion of interleukin (IL)-12 and transforming growth factor (TGF)-β by tissues and their presence was correlated with tumor invasion by intestinal bacteria, especially Fusobacterium nucleatum. Thus, functionally distinct subpopulations of tumor-infiltrating FOXP3(+) T cells contribute in opposing ways to determining CRC prognosis. Depletion of FOXP3(hi) Treg cells from tumor tissues, which would augment antitumor immunity, could thus be used as an effective treatment strategy for CRCs and other cancers, whereas strategies that locally increase the population of FOXP3(lo) non-Treg cells could be used to suppress or prevent tumor formation.

GaAlAs laser-induced pulp mineralization involves dentin matrix protein 1 and osteopontin expression

OBJECTIVES

GaAlAs lasers induce pulp mineralization by promoting reparative dentinogenesis. This study analyzed the expression of dentin matrix protein 1 (DMP1) and osteopontin in GaAlAs laser-irradiated rat molars, to examine the hypothesis that these proteins play a role in the laser-induced reparative dentinogenic process.

MATERIALS AND METHODS

The mesial surfaces of the upper first molars of 8-week-old Wistar rats were irradiated with a pulsed GaAlAs laser. After 1-14 days, mRNA expression of DMP1 and osteopontin in the coronal pulp was analyzed using real-time PCR. DMP1, osteopontin, and heat shock protein 25 (HSP25) were immunolocalized at 1-21 days.

RESULTS

The pulp exhibited a degenerative zone in its mesial portion on days 1-3, and progressive formation of reparative dentin lined with HSP25-immunoreactive odontoblast-like cells, from day 7 onwards. DMP1 and osteopontin mRNA expression were significantly upregulated on days 1-7 and 3-7, respectively. From day 7 onwards, DMP1 and osteopontin immunoreactivity colocalized along the boundary between the primary and reparative dentin.

CONCLUSION

GaAlAs laser irradiation of rat molars induced upregulated DMP1 and osteopontin mRNA expression in the coronal pulp, followed by the formation of reparative dentin and the colocalization of DMP1 and osteopontin immunoreactivity at the site at which this tissue first appeared.

Treating type-1 diabetes with an epigenetic drug

A single drug treats type-1 diabetes in mice by dampening inflammation and enhancing insulin production.

Epigenetic control of thymic Treg-cell development

Thymus-derived Treg cells, which express the transcription factor Foxp3, form a functionally stable cell lineage indispensable for the maintenance of immunological self-tolerance and homeostasis. Foxp3 is critically required for Treg-cell function, in particular for their suppressive function. Recent studies have implicated the contribution of Treg-cell-specific epigenetic modifications as a means to ensure the stable expression of Foxp3 and other molecules associated with Treg-cell function. Unexpectedly, epigenetic modifications introduced in the course of thymic Treg-cell development were found to be independent of Foxp3 expression. These findings require reconsideration of the current model of Treg-cell development based on Foxp3 induction. With reference to other examples of lineage specification, we discuss possible models for thymic Treg-cell development.

Continuous T cell receptor signals maintain a functional regulatory T cell pool

Regulatory T (Treg) cells maintain immune homeostasis and prevent inflammatory and autoimmune responses. During development, thymocytes bearing a moderately self-reactive T cell receptor (TCR) can be selected to become Treg cells. Several observations suggest that also in the periphery mature Treg cells continuously receive self-reactive TCR signals. However, the importance of this inherent autoreactivity for Treg cell biology remains poorly defined. To address this open question, we genetically ablated the TCR of mature Treg cells in vivo. These experiments revealed that TCR-induced Treg lineage-defining Foxp3 expression and gene hypomethylation were uncoupled from TCR input in mature Treg cells. However, Treg cell homeostasis, cell-type-specific gene expression and suppressive function critically depend on continuous triggering of their TCR.

Detection of T cell responses to a ubiquitous cellular protein in autoimmune disease

T cells that mediate autoimmune diseases such as rheumatoid arthritis (RA) are difficult to characterize because they are likely to be deleted or inactivated in the thymus if the self antigens they recognize are ubiquitously expressed. One way to obtain and analyze these autoimmune T cells is to alter T cell receptor (TCR) signaling in developing T cells to change their sensitivity to thymic negative selection, thereby allowing their thymic production. From mice thus engineered to generate T cells mediating autoimmune arthritis, we isolated arthritogenic TCRs and characterized the self antigens they recognized. One of them was the ubiquitously expressed 60S ribosomal protein L23a (RPL23A), with which T cells and autoantibodies from RA patients reacted. This strategy may improve our understanding of the underlying drivers of autoimmunity.

Homeostasis of thymus-derived Foxp3+ regulatory T cells is controlled by ultraviolet B exposure in the skin

Accumulating evidence shows that immunological tolerance induced by Ag administration together with UVB irradiation is dependent on Foxp3(+) CD4(+) regulatory T (Treg) cells. However, the mechanisms by which UVB controls Treg cells in the skin are currently unclear. In this study, we have shown that exposure to UVB induced expansion of Treg cells up to 50-60% of the CD4(+) T cells in the irradiated skin. The Treg cell expansion in the skin lasted for 2 wk after exposure, which contributed to homeostasis of Treg cells in the periphery later. UVB-expanded Treg cells formed clusters with dendritic cells and proliferated in situ. Furthermore, the expanded Treg cells appeared to derive from neuropilin 1(+) thymus-derived Treg (tTreg) cells in the periphery because UVB-expanded Treg cells possessed Treg cell-specific CpG hypomethylation pattern, as seen in tTreg cells. These results collectively indicate that homeostasis of tTreg cells is controlled by UVB exposure in the skin. UVB therapy may be useful for not only inflammatory skin disorders, but also autoimmunity, transplantation, and allergy.

GLCCI1 variant accelerates pulmonary function decline in patients with asthma receiving inhaled corticosteroids

BACKGROUND

In steroid-naive patients with asthma, several gene variants are associated with a short-term response to inhaled corticosteroid (ICS) treatment; this has mostly been observed in Caucasians. However, not many studies have been conducted for other ethnicities. Here, we aimed to determine the relationship between the annual decline in forced expiratory flow volume in one second (FEV1 ) and the variant of the glucocorticoid-induced transcript 1 gene (GLCCI1) in Japanese patients with asthma receiving long-term ICS treatment, taking into account the effect of high serum periostin levels, a known association factor of pulmonary function decline and a marker of refractory eosinophilic/Th2 inflammation.

METHODS

In this study, 224 patients with asthma receiving ICS treatment for at least 4 years were enrolled. The effects of single-nucleotide polymorphisms (SNPs) in GLCCI1, stress-induced phosphoprotein 1 (STIP1), and T gene on the decline in FEV1 of 30 ml/year or greater were determined.

RESULTS

Besides the known contributing factors, that is, the most intensive treatment step, ex-smoking, and high serum periostin levels (≥95 ng/ml), the GG genotype of GLCCI1 rs37973, and not other SNPs, was independently associated with a decline in FEV1 of 30 ml/year or greater. When patients were stratified according to their serum periostin levels, the GG genotype of rs37973 was significantly associated with blood eosinophilia (≥250/μl) in the high serum periostin group.

CONCLUSIONS

A GLCCI1 variant is a risk factor of pulmonary function decline in Japanese patients with asthma receiving long-term ICS treatment. Thus, GLCCI1 may be associated with response to ICS across ethnicities.

Development and maintenance of regulatory T cells

Regulatory T (Treg) cells are a developmentally and functionally distinct T cell subpopulation that is engaged in sustaining immunological self-tolerance and homeostasis. The transcription factor Foxp3 plays a key role in Treg cell development and function. However, expression of Foxp3 alone is not sufficient for conferring and maintaining Treg cell function and phenotype. Complementing the insufficiency, Treg-cell-specific epigenetic changes are also critical in the process of Treg cell specification, in regulating its potential plasticity, and hence in establishing a stable lineage. Understanding how epigenetic alterations and Foxp3 expression coordinately control Treg-cell-specific gene regulation will enable better control of immune responses by targeting the generation and maintenance of Treg cells.

Molecular determinants of regulatory T cell development: the essential roles of epigenetic changes

Regulatory T (Treg) cells constitute a distinct T cell subset, which plays a key role in immune tolerance and homeostasis. The transcription factor Foxp3 controls a substantial part of Treg cell development and function. Yet its expression alone is insufficient for conferring developmental and functional characteristics of Treg cells. There is accumulating evidence that concurrent induction of Treg-specific epigenetic changes and Foxp3 expression is crucial for lineage specification and functional stability of Treg cells. This review discusses recent progress in our understanding of molecular features of Treg cells, in particular, the molecular basis of how a population of developing T cells is driven to the Treg cell lineage and how its function is stably maintained.

Treg cells acquire new directions, cytokines navigate

Foxp3(+) Treg cells express transcription factors normally expressed by specific T helper cells at sites of inflammation. In this issue of Immunity, Koch et al. (2012) and Hall et al. (2012) demonstrate that IFN-γ and IL-27 distinctly induces T-bet(+) Treg cells via STAT-1 transcription factor activation.